1. Field of the Invention
This invention relates to an improvement in the structure of a door frame.
2. Description of the Prior Art
It has been found that the conventional door frames can be roughly divided into five kinds. FIG. 1 illustrates a most commonly used wooden door. However, such a door will corrode and be easily deformed in damp condition. Hence, a door made of fiber reinforced plastic (see FIG. 2) has been developed to obviate these drawbacks, but the door will produce poison gas in case of fire and cannot be recycled. The aluminum door (see FIG. 3) is too dull in appearance and cannot effectively separate sound from one side to the other. FIG. 4 shows a metal door which is too expensive in cost. FIG. 5 illustrates a specially designed wooden door which is inflammable and will easily corrode in damped condition.
Therefore, it is an object of the present invention to provide a structure of a door frame which can obviate and mitigate the above-mentioned drawbacks.